In particular, the exhaust fumes of internal combustion engines are increasingly being cleaned of the impurities or contaminants contained therein which are dangerous to health and to the environment. For example, in diesel engines soot filters of ceramic material are used, which are inserted into the exhaust system. The hot engine exhaust fumes flow into the inlet channels of the filter body, penetrate the porous filter walls surrounding the channels and are then again discharged through the outlet channels. Because of the high temperature, the soot, i.e., carbon, is transformed within the filter walls into gas and ash, which are then blown out of the exhaust system together with the exhaust fumes.
Ceramic filter bodies, however, have several disadvantages. In particular, they are sensitive to rapid changes of temperature, local overheating due to exhaust fumes, and jolts and knocks.
In the somewhat older West German Patent Application P 38 18 281 by the same applicant, an exhaust fume filter has already been suggested, in which the filter body consists of a plurality of compression molded, high temperature-resistant sintered elements. The individual sintered elements, which are of identical design, are jointly connected together into a filter body. The connection can take place, for example, by a sintering operation or by welding.
A connection by a sintering operation is relatively expensive, and the form is in this case finally determined. Weld connections are more adaptable and, where required, can also be subsequently modified. A disadvantage here, however, is that thermal stresses may occur during welding, and these may lead to corrosion problems.